As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EXIT LIGHTS IN UPPER DECK FLASH ON AND OFF. CEILING PANEL REMOVED L-AISLE BETWEEN DOOR-1L & DOOR-2L B-ZONE TO SEARCH FOR BATTERY PACK. BATTERY PACK IS PROBABLY ATTACHED TO UNDERSIDE OF UPPER DK FLOORBOARD, ABOVE L-AISLE, APPROX 6 WINDOWS AFT OF DOOR-1L. BATTERY PACK PCN:585-4495 ETA 1300 FROM LAX, OSTF Y4338. EEL EXIT SIGNS ON BOTH UD DOORS TURN ON DURING FLT. REPLACED POWER SUPPLY M5934 AND M5937 PER MM AND OPS CHECKS OKAY.